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    3.0.0-alpha.5 • Public • Published

    Middy http-multipart-body-parser middleware

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    HTTP json body parser middleware for the middy framework, the stylish Node.js middleware engine for AWS Lambda

    Automatically parses HTTP requests with content type multipart/form-data and converts the body into an object. Also handles gracefully broken JSON as UnprocessableEntity (422 errors) if used in combination with httpErrorHandler.

    It can also be used in combination with validator so that the content can be validated.

    Note: by default this is going to parse only events that contain the header Content-Type (or content-type) set to multipart/form-data. If you want to support different casing for the header name (e.g. Content-type) then you should use the httpHeaderNormalizer middleware before this middleware.


    To install this middleware you can use NPM:

    npm install --save @middy/http-multipart-body-parser


    • busboy (object) (optional): defaults to {} and it can be used to pass extraparameters to the internal busboy instance at creation time. Checkout the official documentation for more information on the supported options.

    Note: this middleware will buffer all the data as it is processed internally by busboy, so, if you are using this approach to parse significantly big volumes of data, keep in mind that all the data will be allocated in memory. This is somewhat inevitable with Lambdas (as the data is already encoded into the JSON in memory as Base64), but it's good to keep this in mind and evaluate the impact on you application.
    If you really have to deal with big files, then you might also want to consider to allowing your users to directly upload files to S3

    Sample usage

    import middy from '@middy/core'
    import httpHeaderNormalizer from '@middy/http-header-normalizer'
    import httpMultipartBodyParser from '@middy/http-multipart-body-parser'
    const handler = middy((event, context) => {
      return {}
    // invokes the handler
    const event = {
      headers: {
        'Content-Type': 'multipart/form-data; boundary=----WebKitFormBoundaryppsQEwf2BVJeCe0M'
      body: 'LS0tLS0tV2ViS2l0Rm9ybUJvdW5kYXJ5cHBzUUV3ZjJCVkplQ2UwTQ0KQ29udGVudC1EaXNwb3NpdGlvbjogZm9ybS1kYXRhOyBuYW1lPSJmb28iDQoNCmJhcg0KLS0tLS0tV2ViS2l0Rm9ybUJvdW5kYXJ5cHBzUUV3ZjJCVkplQ2UwTS0t',
      isBase64Encoded: true
    handler(event, {}, (_, body) => {
      t.is(body,{ foo: 'bar' })

    Middy documentation and examples

    For more documentation and examples, refers to the main Middy monorepo on GitHub or Middy official website.


    Everyone is very welcome to contribute to this repository. Feel free to raise issues or to submit Pull Requests.


    Licensed under MIT License. Copyright (c) 2017-2022 Luciano Mammino, will Farrell, and the Middy team.

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    npm i @middy/http-multipart-body-parser

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    • lmammino
    • middyjs
    • willfarrell